1. The Field of the Invention
This invention relates to tape recording heads, and more particularly to tape recording heads configured to compensate for magnetic tape shrinkage and expansion.
2. The Relevant Art
Magnetic recording has played an important role in the electronic age for permanently storing and retrieving data. Within the field of magnetic recording, few media technologies have been used as extensively as magnetic tape. Magnetic tape has been widely used to store music, video, as well as digital data processed by computers. However, as other types of magnetic media, such as hard drives, have become more economical and capable of storing larger quantities of data, reliance on magnetic tape for data storage has declined.
Part of this decline may be attributed to perceptions of lower reliability of tape, or to slower storage or retrieval of data therefrom. Reliability concerns originate in part from the fact that magnetic tape is prone to shrink and expand due to changes in environmental temperature, humidity, creep caused by tension on the tape, or creep caused by the tendency of an extruded material, such as tape, to return to a previous form.
Nevertheless, using tape for data storage still provides significant advantages, including its relatively low cost and large storage capacity. Very few other technologies offer the combined low cost and high capacity advantage of tape. While other technologies may offer various advantages with respect to tape in specific areas, overall, none of these technologies compare to tape in addressing customer needs for low cost and storage capacity.
As is customary with other storage mediums, significant effort is directed to storing larger quantities of data on smaller areas of the medium (e.g. increasing storage density). Moreover, additional effort is directed to storing and retrieving the data faster and more efficiently. As data is stored on tape in increased density, one issue becomes reliably writing and retrieving data stored on smaller and smaller areas of the tape.
For example, in order to accurately store and retrieve data from tape, data recording and reading heads need to be accurately positioned with respect to the tape surface. The complexity of this task is compounded by possible changes in a tape's dimensions. Even slight amounts of tape distortion may make the retrieval of written information difficult if not impossible.
Problems incurred by the dimensional instability of tape and its limitations with respect to track density in multi-read element systems is well known in the art. One proposed solution is to place the elements of a multi-element head closer together. However, existing heads are as close together as current technology allows.
Another approach is to skew a recording head with respect to the magnetic tape such that rotation of the head varies the effective span of the head over tracks on the tape. However, skewing the head causes problems when reading the data. Moreover, due to the “cosine” characteristics of skewing the head, a relatively large skew is required to significantly affect the span of the head over the tape.
Thus, in accordance with the previously stated concerns, apparatus and methods are needed to more accurately store and retrieve data from magnetic tape using recording and reading heads. What is further needed are apparatus and method to accurately store and retrieve data while compensating for expansion or shrinkage of tape due to humidity, temperature, or creep.
Accordingly, it would be an advance in the art to provide a recording head that could accurately store and retrieve data on tape even when the tape has changed dimensions due to humidity, temperature, creep, or other causes.